From patchwork Mon Mar 25 08:06:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiaoyao Li X-Patchwork-Id: 10868157 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D4BA1669 for ; Mon, 25 Mar 2019 08:07:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0BEF729257 for ; Mon, 25 Mar 2019 08:07:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F3E8729261; Mon, 25 Mar 2019 08:07:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7E3CE29257 for ; Mon, 25 Mar 2019 08:07:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729993AbfCYIHW (ORCPT ); Mon, 25 Mar 2019 04:07:22 -0400 Received: from mga17.intel.com ([192.55.52.151]:50930 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729986AbfCYIHW (ORCPT ); Mon, 25 Mar 2019 04:07:22 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Mar 2019 01:07:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,256,1549958400"; d="scan'208";a="134474072" Received: from lxy-server.sh.intel.com ([10.239.48.11]) by fmsmga008.fm.intel.com with ESMTP; 25 Mar 2019 01:07:19 -0700 From: Xiaoyao Li To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Xiaoyao Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, chao.gao@intel.com, Sean Christopherson Subject: [PATCH v3 2/2] x86/vmx: optimize MSR_MISC_FEATURES_ENABLES switch Date: Mon, 25 Mar 2019 16:06:50 +0800 Message-Id: <20190325080650.19896-3-xiaoyao.li@linux.intel.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190325080650.19896-1-xiaoyao.li@linux.intel.com> References: <20190325080650.19896-1-xiaoyao.li@linux.intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP KVM needs to switch MSR_MISC_FEATURES_ENABLES between host and guest in every pcpu/vcpu context switch. Since WRMSR is expensive, this patch tries to save cycles by avoiding WRMSR MSR_MISC_FEATURES_ENABLES whenever possible. If host's value is zero, nothing needs to be done, since guest can use kvm emulated cpuid faulting. If host's value is non-zero, it need not clear MSR_MISC_FEATURES_ENABLES unconditionally. We can use hardware cpuid faulting if guest's value is equal to host'value, thus avoid WRMSR MSR_MISC_FEATURES_ENABLES. Since hardware cpuid faulting takes higher priority than CPUID vm exit, it should be updated to hardware while guest wrmsr and hardware cpuid faulting is used for guest. Signed-off-by: Xiaoyao Li --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/vmx/vmx.c | 13 ++++++++++--- arch/x86/kvm/x86.c | 15 ++++++++++++--- 3 files changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 2c53df4a5a2a..9bcb444b903d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1343,6 +1343,8 @@ void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw); void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l); int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr); +int kvm_supported_msr_misc_features_enables(struct kvm_vcpu *vcpu, u64 data); + int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr); int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 65aa947947ba..73bb11f74b36 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1035,10 +1035,10 @@ static void vmx_prepare_guest_misc_features_enables(struct vcpu_vmx *vmx) { u64 msrval = this_cpu_read(msr_misc_features_shadow); - if (!msrval) + if (!msrval || msrval == vmx->vcpu.arch.msr_misc_features_enables) return; - wrmsrl(MSR_MISC_FEATURES_ENABLES, 0ULL); + wrmsrl(MSR_MISC_FEATURES_ENABLES, vmx->vcpu.arch.msr_misc_features_enables); } void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) @@ -1136,7 +1136,7 @@ static void vmx_load_host_misc_features_enables(struct vcpu_vmx *vmx) { u64 msrval = this_cpu_read(msr_misc_features_shadow); - if (!msrval) + if (!msrval || msrval == vmx->vcpu.arch.msr_misc_features_enables) return; wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval); @@ -2043,6 +2043,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) else vmx->pt_desc.guest.addr_a[index / 2] = data; break; + case MSR_MISC_FEATURES_ENABLES: + if (!kvm_supported_msr_misc_features_enables(vcpu, data)) + return 1; + if (this_cpu_read(msr_misc_features_shadow) && vmx->loaded_cpu_state) + wrmsrl(MSR_MISC_FEATURES_ENABLES, data); + vcpu->arch.msr_misc_features_enables = data; + break; case MSR_TSC_AUX: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP)) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ad1df965574e..d2af90422a51 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2449,6 +2449,17 @@ static void record_steal_time(struct kvm_vcpu *vcpu) &vcpu->arch.st.steal, sizeof(struct kvm_steal_time)); } +int kvm_supported_msr_misc_features_enables(struct kvm_vcpu *vcpu, u64 data) +{ + if (data & ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT || + (data & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT && + !supports_cpuid_fault(vcpu))) + return 0; + else + return 1; +} +EXPORT_SYMBOL_GPL(kvm_supported_msr_misc_features_enables); + int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) { bool pr = false; @@ -2669,9 +2680,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.msr_platform_info = data; break; case MSR_MISC_FEATURES_ENABLES: - if (data & ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT || - (data & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT && - !supports_cpuid_fault(vcpu))) + if (!kvm_supported_msr_misc_features_enables(vcpu, data)) return 1; vcpu->arch.msr_misc_features_enables = data; break;